After getting a van here with zero compression on one cylinder I wanted to
test whether the compression was leaking past the valves or the rings (the
cylinder head gasket seemed fine as no abnormal pressure was being generated
in the coolant system).  The customer had taken the van to a local dealer who
did a leak down test and found that it was leaking past the rings.  I wanted
to double check thier findings (they have been wrong before) but I wanted to
do it simply/quickly.

Here is what I did:
1.  Unhook and ground the wire coming from the coil to the distributor cap on
the cap end.
2.  Unhook the rubber hose coming from the crankcase vent "tower".
3.  Crank the engine over using your handy remote starter (or an assitant if
you don't have one of these).
4.  If lots of air pressure and maybe even a little wisp of smoke is coming
out of the crankcase breather "tower" then you are leaking compression past
the rings.  If not then you are leaking it past the valves (it is either one
or the other).

This simple method basically tells you if you rings are OK or not and wether
putting on a rebuilt head will solve your low compression problem or if it is
time for a rebuild (if you are going to re-ring why not tear the thing down
and do it right?)

Hope this helps,
Ken Wilford
http://www.vanagain.com
John 3:16
Phone: (856)-765-1583
Shop:   (856)-327-0027
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